Means for cleaning pipelines

ABSTRACT

A pipeline-cleaning travelling &#39;&#39;&#39;&#39;pig&#39;&#39;&#39;&#39; ball having a generally spherical main body formed of a resiliently deformable material. The main body of the ball is provided with plurality of discrete, discontinuous, spaced-apart protuberances upstanding from the surface thereof; the protuberances being of a hardness greater than that of the main body. Preferably, the protuberances are spaced substantially uniformly over the spherical surface of the main body. The invention also contemplates the provision of a pipeline-cleaning kit comprising a first lead &#39;&#39;&#39;&#39;pig&#39;&#39;&#39;&#39; ball and a second follower pig ball; the second or follower pig ball having a main body formed of a resiliently deformable material having a hardness greater than the hardness of the main body of the first or leading pig ball.

United States Patent Schultz [54] MEANS FOR CLEANING PIPELINES [72]Inventor: Ronald W. Schultz, Lodgepole, Alberta,

Canada [22] Filed: Dec. 8, 1970 [21] Appl.No.: 96,187 V V Related U. S.Application Data [62] Division of Ser. No. 751,844, Aug. 12, 1968, Pat.

1 51 Mar. 28, 1972 Primary Examiner-Edward L. Roberts Attorney-Milieu,Raptes & White 571 ABSTRACT A pipeline-cleaning travelling pig" ballhaving a generally spherical main body formed of a resilientlydeformable material. The main body of the ball is provided withplurality of discrete, discontinuous, spaced-apart protuberancesupstanding from the surface thereof; the protuberances being of ahardness greater than that of the main body. Preferably, theprotuberances are spaced substantially uniformly over the sphericalsurface of the main body. The invention also contemplates the provisionof a pipeline-cleaning kit comprising a first lead pig ball and a secondfollower pig ball; the second or follower pig ball having a main bodyformed of a resiliently deformable material having a hardness greaterthan the hardness of the main body of the first or leading pig ball.

17 Claims, 5 Drawing Figures Patented March 28, 1972 3,651,530

RONALD W. SCHULTZ INVENTOR ATTORNEY MEANS FOR CLEANING PIPELINES Thisapplication is a division of copendingapplication Ser.

This invention relates to cleaners forpipelines, andin particular to anovel go-devil or pig for the cleaning. of pipelines.

In industry pipelines are used for conveying fluids under pressure fromone place to another and in all cases it is desirable that the flow offluid should be free and-unimpaired, both with-regard to volume and alsoto velocity, and the relationship of these two factors to each othershouldbe fairly constant. In use, these pipelines to a greater or lessdegree become fouled or partially clogged by a buildup. of scale,thereby reducing the effective area of thepipeline and'increasing thefrictional resistance to the flow of liquid through the pipeline. Itthus becomes necessary periodically to clean the pipeline; Among some ofthe methods used for cleaning suchpipeline's are the use of acids orother chemicals, sand blasting (if the pipe can be disconnected), orpipeline-cleaning'pigs. If such cleaning involves the shutting down ofthe pipeline and/or the disconnecting of any parts of the pipeline, thenthe efficiency" of the line becomes impaired due to loss of the workhours during which the line is out of commission. The character of theliquid beingconveyed through the pipeline may influence the speed andfrequency of the fouling of the pipeline, and a heavy and more viscousfluid' may tend'tofoul a pipeline quicker than a light fluid. Whateverbe the characteristics'of the fluids, it will be appreciated that,unless the pipeline is maintained in proper serviceable condition, thenmonetary. loss in the operation of'the pipeline becomes high.

As is now well known, the pipeline transportation industry extensivelyuses travelling plugs, such as spherical members called pig balls, inpipelines for the purposeof effecting such defouling. One field ofgeneral use is in the flow line through V which crude oil produced by anoil well is transferred to the;

tank battery. In certain areas this line becomes coated on the insidewith a layer of wax which is deposited by the oiLThis layer becomesthicker as the oil continues" to flow, and sometimes plugs the flow linecompletely. By insertinga ball,some-' times referred to as a pig ball,in theline atthe well head, the oil pressure will force 'it through theflow line scraping out the wax ahead of it. The pipeline is oftencomprised of a plurality of diameter sizes, and it is desirable toinject a sphere or plug at intervals along the pipeline in accordancewith the diameter variances therein. Furthermore, since the pipeline maybe formed of a plurality of welded-together sections, a slight decreasein internal diameter of the pipeline at a join occurs as a result of thewelding bead. Fouling and/or buildup tends to occur at such locations.In the use of these balls which pass through the line along with theliquid travelling in the line, the industry has now provided many kindsof apparatus to launch or inject the spheres into the line and differingschemes to remove the spheres from the lines at predetermined points. Asnow used in the art; the term pig ball has come to refer to 'a sphericalbody of solid or inflatable material, e.g., rubbery material, whichcleans out pipelines. The pig ball is forced through the pipeline,cleaning as it travels. Generally, the pig ball has a diameter slightlylarger than the internal diameter of the pipeline and acts as a freeplunger as it is driven by fluid (liquid or air) pressure through thelength of the pipeline.

Pig balls, as now known in the art, may be inflatable, flexible andhollow spheres, or they may be rigid plastic compositions, or flexible,solid spheres. They may be made of a rubbery material such aspolychloroprene, commercially available as Neoprene. They may be solidor inflatable, and usually are slightly larger in diameter than theinside diameter of the pipeline to be pigged.

Pigging a pipeline is a term used to describe an operation wherein a pigball is inserted into a pipeline for separation of products, or when thepipeline is to be completely emptied of fluid or when removing coateddebris from the inner walls of a pipeline. The ball efiectivelysqueegees the pipe walls as it passes through the'pipeline. A uniformfluid pressure on one side of the ball moves it forwardagainst inertiaand resistance when the ball isproperly started on its way into thepipeline.

It is an object of this invention to provide a novel pig ball for thecleaning of pipelines. An object of another aspect of this invention isthe provision of a novel kit for the cleaning of pipelines;

In accordance with this invention, a travelling pipelinecleaning pigball comprises a generally spherical main body formed of a resilientlydeformable material, and provided with a plurality of discrete,discontinuous, spaced-apart protuberances upstanding from its surface.The protuberances are harder than the main body of the ball, andpreferably are spaced substantially uniformly over the spherical surfaceof the main body.

By anotheraspect of this invention there is provided a kit for thecleaning of pipelines. The kit comprises the combination of (a) a firstlead pipeline cleaning travelling pig ball having a generally sphericalmain body formed of a resiliently deformable'mate rial and provided witha plurality of discrete, discontinuous and spaced apart protuberancesupstanding from the surface thereof, said protuberances having ahardness greater than that of said main body, and (b) a second followerpipeline-cleaning travelling pig ball having a generally spherical mainbody formed of a resiliently deformable material and provided with aplurality of discrete, discontinu ous and laterally spaced apartprotuberances upstanding from the surface thereof, said protuberanceshaving a hardness greater than'that of said main body, and said mainbody having a hardness greater than the hardness of the main body ofsaid lead pig ball.

It is important that the pig balls be resiliently deformable, but theprecise material out 'of which the pig ball is formed may be selectedfrom a wide variety of substances. The pig ball may be a-solid or ahollow plastic or rubber (natural or synthetic) which is of sufficientresiliency as to be able to be forced through a pipeline and to beresiliently deformed by permanent obstructions in the pipeline-but besubstantially undeformed by temporary obstructions, e.g., scale buildupwithin the pipeline. Thus, dependingon the particular use to which thepig ball may be put and the type of scale within the pipeline, theresiliently deformable material may be a soft" material, e'.g., have aShore A Durometer hardness of 30 50; a semi-hard" substance, e.g., havea Shore A Durometer hardness of 50 or a"hard material, e.g., have aShore A Durometer hardness above 100. Among the rubbers which may beused and which would be selected to have the appropriate hardness are:natural rubber; butadiene-styrene copolymers (e.g., Buna S);butadiene-acrylonitrile copolymers (e.g., Perbunan, Hycar, Chemigum);polychloroprenes (e.g., Neoprene); isobutylene diolefin copolymers(e.g., Butyl); polysulfide rubbers (e.g., Thiokols,

- Perdurens); and polybutene rubbers (e.g.', Vistanex, polybutene). Inaddition, some vinyl resins are also useful, (e.g Koroseal, Flamenol,Igelite, Mipolom, Vinylite V).

A particular embodiment of this invention now will be described, makingreference to the drawings which accompany this specification in which:

FIG. I is a front elevation view of a pig ball according to thisinvention.

FIG. 2 is a cross section view taken along the line lI--Il of FIG. 1.

FIG. 3 is a cross section view similar to that of FIG. 2 but showing analternative structure of pig ball according to the practice of thisinvention.

FIG. 4 is a cross section view similar to that of FIGS. 2 and 3, butshowing another alternative embodiment of a pig ball of this invention.FIG. 5 is a schematic representation of pig balls of the presentinvention passing through a pipeline.

The pig balls 10 are provided with a plurality of spacedapartprotuberances upstanding from the surface thereof, which are harder thanthe main ball. The protuberances 12 are for the purpose of enhancing thecleaning action by knocking,

cutting or scraping away sedimentary or other deposits from the insideof the pipeline. While the protuberances 12 should be harder than themain ball, they need not be formed of a different material. Thus, theprotuberances 12 may be formed of the same material (chemically) buthaving the necessary degree of hardness. The protuberances, if formed ofthe resiliently deformable material 11, should be provided with hardmetal tips 13. Alternatively, the protuberances may be formed of hardmetal 16 suitably secured to the spherical surface of the main ballwhich, as shown in FIG. 4, is a hollow resiliently deformable ball 15.They may, for example, be in the form of lugs to knock sedimentarydeposits from the inside of the pipeline. They also may be sharpened tofunction as scrapers or cutters to clean the pipeline of such deposits.

One preferred type of protuberance is tungsten carbide studs 14 (FIG.3). The studs are generally embedded in holes 17 drilled in theresiliently deformable ball 11.

FIG. shows a pipeline 20 being cleaned utilizing pig balls in accordancewith this invention. The pipeline 20 is provided with the usual controlvalves (not shown) and with a conventional means well known to thoseskilled in the art for injecting pig balls into the pipeline 20 and forremoving the pig balls after they have traversed the portion of thepipeline to be cleaned. A pig ball 101 is injected into the pipeline 20by conventional means, and is propelled along the pipeline by the fluidpressure therewithin. After a predetermined interval of time, a secondpig ball 102 is similarly injected into the pipeline and both pig balls101 and 102 are propelled along the pipeline 20 by fluid pressure, thepig balls remaining in spaced-apart relation. If desired, additional pigballs (not shown) may be injected into the pipeline 20. After each pigball has traversed the portion of the pipeline 20 to be cleaned, it isremoved by conventional means and the loosened sediment and otherfouling material is also withdrawn.

There is no criticality in the disposition of the protuberances on thesurface of the ball. Thus, they may be more or less equidistantlyspaced, or they may be fairly densely arrayed and offset to have anirregular pattern. Generally, having a protuberance at every one-halfsquare inch of the surface is satisfactory. The protuberances aregenerally one-fourth to three-eighth inches high, i.e. they extendoutwardly by that amount from the surface.

In one example, a pipeline three-fourths mile long and having a nominalinternal diameter of 3 inches, was cleaned utilizing the pig balls ofthis invention. The first or lead pig ball was a solid ball formed ofNeoprene provided with a plurality of tungsten carbide protuberancesspaced at 1% inch centers. It had a Shore A Durometer hardness of 50 andan external diameter of 3 inches. The second or follower pig ball was asolid ball formed of Hycar. It too was provided with a plurality oftungsten carbide protuberances spaced at 1& inch centers, but it had aShore A Durometer hardness of 50 and an external diameter of 3 inches.An applied force of 50 p.s.i. was required to propel the pig ballsthrough the pipeline so as to clean the line. For a pipeline 2 mileslong, using the same pig balls, a force of 80 p.s.i. was required. Thiscompares favorably with the sand blast technique, where, for a pipeline2 miles long, a force of 800 1,200 p.s.i. created by a 2 hp. motor isneeded.

Iclaim:

1. A pipeline-cleaning travelling pig ball having a generally sphericalmain body formed of a resiliently deformable material, and provided witha plurality of discrete, discontinuous, spaced-apart protuberancesupstanding from the surface thereof, said protuberances having ahardness greater than 4 that of the main body.

2. A pipeline-cleaning ball as defined in claim 1 wherein saidprotuberances are spaced substantially uniformly over the surface of themain body.

3. A pipeline-cleaning ball as defined in claim 2 wherein theresiliently deformable material is natural or synthetic rubber.

4. A pig of claim 3 wherein the rubber has a Shore A Durometer hardnessof 30 to 100.

5. The pig of claim 2 wherein the protuberances are formed of a materialdifferent from that of the main body.

6. The pig of claim 5 wherein said protuberances are provided with hardmetal tips.

7. The pig of claim 5 wherein said protuberances are formed of hardmetal.

8. The pig of claim 7 wherein the hard metal protuberances are attachedto the surface of the main body.

9. The pig of claim 5 wherein the protuberances are formed of orprovided with tips of tungsten carbide.

10. The pig of claim 9 wherein the resiliently deformable material ofthe main body is natural or synthetic rubber.

11. A kit for cleaning pipeline comprising the combination of:

a. a first lead pipeline-cleaning travelling pig ball having a generallyspherical main body formed of a resiliently deformable material andprovided with a plurality of dis crete, discontinuous and spaced apartprotuberances having a hardness greater than that of said main body, and

b. a second follower pipeline-cleaning travelling pig ball having agenerally spherical main body formed of a resiliently deformablematerial and provided with a plurality of discrete, discontinuous andlaterally spaced apart protuberances upstanding from the surfacethereof, said protuberances having a hardness greater than that of saidmain body, and said main body having a hardness greater than thehardness of the main body of said lead pig ball.

12. A pipeline cleaning kit as defined in claim 11 wherein theresiliently deformable material forming the main body of said first leadpig ball is a natural or synthetic rubber having a Shore A Durometerhardness between 30 and 50, and wherein the resiliently deformablematerial forming the main body of said second follower pig ball is anatural or synthetic rubber having a Shore A Durometer hardness between50 and 100.

13. A pipeline cleaning kit as defined in claim 11 wherein theresiliently deformable material forming the main body of said first leadpig ball is a natural or synthetic rubber having a Shore A Durometerhardness between 30 and 50, and wherein the resiliently deformablematerial forming the main body of said second follower pig ball is anatural or synthetic rubber having a Shore A Durometer hardness greaterthan 100.

14. A pipeline cleaning kit as defined in claim 11 wherein theresiliently deformable material forming the main body of said first leadpig ball is a natural or synthetic rubber having a Shore A Durometerhardness between 50 and 100, and wherein the resiliently deformablematerial forming the main body of said second follower pig ball is anatural or synthetic rubber having a Shore A Durometer hardness greaterthan 100.

15. A pipeline cleaning kit as defined in claim 11 wherein saidprotuberances on saidtravelling pig balls are formed of metal.

16. A pipeline cleaning kit as defined in claim 15 wherein saidprotuberances are provided with hard metallic tips.

17. A pipeline cleaning kit as defined in claim 16 wherein saidprotuberances have tips formed of tungsten carbide.

1. A pipeline-cleaning travelling pig ball having a generally sphericalmain body formed of a resiliently deformable material, and provided witha plurality of discrete, discontinuous, spacedapart protuberancesupstanding from the surface thereof, said protuberances having ahardness greater than that of the main body.
 2. A pipeline-cleaning ballas defined in claim 1 wherein said protuberances are spacedsubstantially uniformly over the surface of the main body.
 3. Apipeline-cleaning ball as defined in claim 2 wherein the resilientlydeformable material is natural or synthetic rubber.
 4. A pig of claim 3wherein the rubber has a Shore A Durometer hardness of 30 to
 100. 5. Thepig of claim 2 wherein the protuberances are formed of a materialdifferent from that of the main body.
 6. The pig of claim 5 wherein saidprotuberances are provided with hard metal tips.
 7. The pig of claim 5wherein said protuberances are formed of hard metal.
 8. The pig of claim7 wherein the hard metal protuberances are attached to the surface ofthe main body.
 9. The pig of claim 5 wherein the protuberances areformed of or provided with tips of tungsten carbide.
 10. The pig ofclaim 9 wherein the resiliently deformable material of the main body isnatural or synthetic rubber.
 11. A kit for cleaning pipelines comprisingthe combination of: a. a first lead pipeline-cleaning travelling pigball having a generally spherical main body formed of a resilientlydeformable material and provided with a plurality of discrete,discontinuous and spaced apart protuberances upstanding from the surfacethereof, said protuberances having a hardness greater than that of saidmain body, and b. a second follower pipeline-cleaning travelling pigball having a generally spherical main body formed of a resilientlydeformable material and provided with a plurality of discrete,discontinuous and laterally spaced apart protuberances upstanding fromthe surface thereof, said protuberances having a hardness greater thanthat of said main body, and said main body having a hardness greaterthan the hardness of the main body of said lead pig ball.
 12. A pipelinecleaning kit as defined in claim 11 wherein the resiliently deformablematerial forming the main body of said first lead pig ball is a naturalor synthetic rubber having a Shore A Durometer hardness between 30 and50, and wherein the resiliently deformable material forming the mainbody of said second follower pig ball is a natUral or synthetic rubberhaving a Shore A Durometer hardness between 50 and
 100. 13. A pipelinecleaning kit as defined in claim 11 wherein the resiliently deformablematerial forming the main body of said first lead pig ball is a naturalor synthetic rubber having a Shore A Durometer hardness between 30 and50, and wherein the resiliently deformable material forming the mainbody of said second follower pig ball is a natural or synthetic rubberhaving a Shore A Durometer hardness greater than
 100. 14. A pipelinecleaning kit as defined in claim 11 wherein the resiliently deformablematerial forming the main body of said first lead pig ball is a naturalor synthetic rubber having a Shore A Durometer hardness between 50 and100, and wherein the resiliently deformable material forming the mainbody of said second follower pig ball is a natural or synthetic rubberhaving a Shore A Durometer hardness greater than
 100. 15. A pipelinecleaning kit as defined in claim 11 wherein said protuberances on saidtravelling pig balls are formed of metal.
 16. A pipeline cleaning kit asdefined in claim 15 wherein said protuberances are provided with hardmetallic tips.
 17. A pipeline cleaning kit as defined in claim 16wherein said protuberances have tips formed of tungsten carbide.